// #pragma GCC optimize("O3")
// #pragma GCC optimization("Ofast,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
using namespace std;
// #define int long long
#define ll long long
#define FOR(i, l, r) for (int i = (l); i <= (r); i++)
#define FOD(i, r, l) for (int i = (r); i >= (l); i--)
#define fi first
#define se second
#define pii pair<int, int>
const ll mod = 1e9 + 7;
const int MAXN = 1e6 + 5;
const ll oo = 1e9 + 7;
const int base = 10;
int n;
string a, b;
int dp[MAXN][4];
bool match(int i, int j) {
char c = (j == 2 ? a[i] : char('0' + j));
return c == b[i];
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
if(!(cin >> n >> a >> b)) return 0;
FOR(i, 0, n){
dp[i][0]=dp[i][1]=dp[i][2]=oo;
}
dp[0][2] = 0;
FOR(i, 0, n-1){
FOR(j, 0, 2){
if(dp[i][j] == oo) continue;
FOR(k, 0, 2){
int cst = dp[i][j];
cst += (j != k && k != 2) ? 1 : 0;
bool chk = (i == 0) ? true : match(i-1, j);
bool chk2 = match(i, k);
cst += (chk && !chk2) ? 1 : 0;
if(cst < dp[i+1][k]) dp[i+1][k] = cst;
}
}
}
int ans = min({dp[n][0], dp[n][1], dp[n][2]});
cout << ans << '\n';
return 0;
}
